Why is there a saying in ancient times that "the sky is square and the earth is round"?

“The round sky and the square earth are a manifestation of the Yin-Yang theory. Chinese traditional culture is extensive and profound, and the Yin-Yang theory is its core and essence. The Yin-Yang theory, with its simple dialectics, is the way of thinking of our country’s sages who understand the world. Thousands of years of social practice have proven its correctness. "The sky is round and the earth is square" is a concrete embodiment of this theory. We know that the ability of ordinary people to perceive the five senses is limited, and this is also the limitation of the development of modern science. Ancient scientists can improve their own energy through the practice of "internal realization", and finally observe the more subtle truth of the universe and the rules of energy operation: Yin and Yang and the Five Elements. Specifically, the Yin and Yang and the Five Elements are divided into many levels, and their concepts are as follows. The unknown numbers "x, y" in the equations in modern mathematics, that is to say, when the equation is solving a specific problem, the unknown numbers such as x and y have specific representations of matter, and when explained from a purely mathematical perspective , x, y are unknown numbers with no specific direction. The ancient Chinese medical classic "Huangdi Neijing" clearly proposed the theory of five movements and six qi. This theory is essentially a summary of the movement and transformation of the energy of heaven and earth at a certain level. The ancients discovered that , every time the energy between heaven and earth changes, it will gradually manifest in the relatively macroscopic world that people can see. For example, when the energy of the "wood" attribute represented by the Eastern Qisu arrives in spring, the earth will thaw and seeds will Beginning to sprout, all life is awakened by this energy and enters a new round of "spring growth, summer growth, autumn harvest, and winter storage". With the changes of the four seasons, the health status of human life will also be affected differently. Therefore, "Yellow Emperor" There is a "Great Treatise on Adjusting the Spirit of the Four Seasons" in the "Nei Jing", which specifically discusses the impact of the yin and yang changes of the four seasons on the human body. The ancients summarized the changes in energy in the microscopic state as the "Five Movements and Six Qi Theory", which is used to measure the relationship between heaven and earth. The relationship between energy changes and time, and the impact of this change on life on earth. This is what the ancients called "timing". The so-called "timing" refers to the arrival of energy from the sky, which is the beginning of the corresponding season. 60 The year comes and goes again and again, like a ring without any reason, so the ancients said "the sky is round" to describe the characteristics of time. At the same time, when the ancients talked about directions, they used "all directions" to describe it, which is also called "the sky is round and the place is". Talking about time and space means talking about the true face of the universe! The concept of time and space embodies the wisdom of our ancestors